1. Field of the Invention
The present invention relates to a power source control circuit for use in an electronic device such as, a television receiver having two kinds of power source turning on/off means. Namely, a main switch is provided in the electronic device for turning off the device when the main switch is turned off and a remote control switch effective only when the main switch is in the "on" position, to turn the device on/off through the use of a remote control, or through a button located on the electronic device. More particularly the present invention relates to a power sour circuit which necessarily turns on the power source of the electronic devices, irrespective of the state of a memory circuit, when the main switch is turned on and maintains the previous on/off state of the power source after a power stoppage occurs.
2. Description of the Related Art
The conventional power source control circuits only operate to maintain the previous on/off state of the power source. FIG. 5 is a block diagram of a conventional relay which turns on/off the power source of an electronic device, which comprises a transistor 9 which drives the relay 8; a non-volatile memory 11 which stores data n the state of the power source; a memory reader 10 which reads the contents of the memory 11 to control the transistor 9.
The operation of the conventional power source control circuit will be described with reference to FIG. 5 in which when the main switch 7 is turned on, the memory reader 10 reads data from the non-volatile memory 11 to see if the previous state of the power source of the electronic device is on. If so, it drives the transistor 9 to thereby drive the relay 8 and hence to operate the electronic device. If the contents read from the memory 11 indicate that the previous state of the power source is off, the memory reader 10 does not drive the transistor 9 and hence the relay 8.
By such operation, the electronic device is not operated even if the main switch 7 is turned on so long as the contents of the non-volatile memory 11 indicate that the previous state of the power source is off.